A. Technical Field
The present invention relates to a distillation process for a solution containing easily polymerizable substances such as (meth)acrylic acid and (meth)acrylic acid ester.
B. Background Art
In a process of distilling a solution containing easily polymerizable substances such as (meth)acrylic acid and (meth)acrylic acid ester, a method comprising the step of adding a polymerization inhibitor and/or supplying a gas containing molecular oxygen is adopted with lowering a temperature as low as possible under a reduced atmosphere in order to suppress a polymerization during distillation.
For example, FIG. 1 illustrates a prior distillation process for an easily polymerizable substance-containing solution, and illustrates a distillation column (1) and a condenser (2). Vapor from an overhead column of the distillation column (1) is supplied upward to a tube side of the condenser (2) and a condensate condensed by cooling water (3) is obtained from a distillate line (13) (a portion of the distillate is introduced into a reflux line (14)). In addition, vapor from the condenser is introduced into a line for atmospheric or vacuum system through a condenser gas outlet line (15).
FIG. 2 illustrates another prior distillation process for an easily polymerizable substance containing-solution, and illustrates a distillation column (1) and a condenser (2). However, vapor from an overhead column of the distillation column (1) is supplied downward to a tube side of the condenser (2) as opposed to FIG. 1 and a condensate condensed by cooling water (3) is obtained from a distillate line (13) (a portion of the distillate is introduced into a reflux line (14)). In addition, vapor from the condenser is introduced into a line for atmospheric or vacuum system through a condenser gas outlet line (15).
However, in these processes representative of the prior distillation process, vapor from the condenser contains an easily polymerizable substance. Therefore, it is under a circumstance impossible to stably operate because polymerized products are formed in a line from a condenser to an ejector or a vacuum pump, in a line from a condenser to an atmosphere or a harm removal equipment, at an outlet of a ejector, or in a vacuum pump, and it is often necessary to stop operation.
A. Object of the Invention
An object of the present invention is to provide: a process can be preventive of a polymerization in a distillation apparatus when distilling a solution containing easily polymerizable substances such as (meth)acrylic acid and (meth)acrylic acid ester.
B. Disclosure of the Invention
The present inventors diligently studied to solve the above-mentioned problems. As a result, they found that: the above-mentioned problems can be solved if a distillation column is now newly equipped with at least one condenser for polymerization inhibition in series on a vapor outlet side of a condenser for condensation as equipped to a vapor outlet of the distillation column and if the vapor from an upstream condenser outlet is supplied to a downstream condenser. They completed the present invention in this way.
That is to say, a distillation process for an easily polymerizable substance-containing solution, according to the present invention, comprises the step of distilling an easily polymerizable substance-containing solution by a distillation column equipped with a condenser for condensation at a vapor outlet of the distillation column, wherein at least one condenser for polymerization inhibition is further placed in series on a vapor outlet side of the condenser for condensation, and wherein the easily polymerizable substance which is contained in vapor from an upstream condenser is condensed by a downstream condenser.
These and other objects and the advantages of the present invention will be more fully apparent from the following detailed disclosure.